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An epidemiological study was conducted recently by the
National Institute of Nutrition (NIN), Hyderabad (India), to know the antioxidant  properties of different fruits. The study included only those fruits that are easily available in the Indian market and are commonly consumed by maximum Indians. The fruits were Guava, Pine-apple, Indian plum, Mango (ripe), Apple, Chiku, Watermelon, Custard apple, Grapes (green), Orange, Papaya (ripe), Pomegranate, Sweetlimeand Banana.

The results showed that out of the 14 fresh fruitsguava and mango were found to be the richest in antioxidants. Anti-oxidant property of guava was found to be 496 mg / 100gm, which is said to be sufficient to get rid of ‘free radicals’ (wear and tear/disease causing chemicals) present in our body. the antioxidant activity of the fruits in the study ranged from as high as 496 mg /100 gm in Guava to as low as 22mg/100gm in pineapple. ‘’Lycopene’’is the potent antioxidant found in abundance in Guava.

A guava provides 2.9 g of  Lycopene, an antioxidant that protects healthy cells from toxins that accumulate in the body due to metabolism and environmental pollution. The damaging effect of toxins includes premature aging, cancer development because they damage DNA in charge of growth and development.

Free radicals hasten ageing and are responsible for causing many Cancers and many other degenerative disorders. So, the main objective behind the study was to know the antioxidant properties in naturally occurring fruits that could fight against free radicals.

The study has brought forth the benefit of the natural occurring antioxidants in lowering the risk of degenerative diseases such as Cancer, Diabetes, Atherosclerosis (hardening of blood channels).

Dr Sreeramulu, from the Endocrinology and Metabolism division of the National Institute of Nutrition’s and the lead author of this study, stated that “Natural antioxidants ”have attracted considerable interest among nutritionists, food manufacturers and consumers because of their presumed safety and potential therapeutic value.

Dr Sreeramulu highlighted the importance of the findings saying that “even the commonly available Guava can enrich the Indian diet”. He also added that “We usually believe expensive fruits are the richest source of nutrition. But our extensive research shows that highly economical fruits like ‘’Guava’’ are rich in antioxidant the most that help scavenge free radicals that destroy tissues. The Indian plum, the custard apple and India’s be loved mangoes, all came after guava in antioxidant richness. The study also found that while there is a presence of antioxidant concentrations of just under 500 mg per 100 gm in guava, 330 mg in plum and 135 mg in pomegranate, apples have a quarter of the antioxidants compared with guava and bananas have a tiny fraction with 30 mg per 100gm.

Cellular damage or oxidative injury arising from free radicals or reactive oxygen species (ROS) now appears to be the fundamental mechanism underlying a number of infections, human neurodegenerative disorders, diabetes, inflammation, viral infections, autoimmune pathologies and digestive disorders. Free radicals are generated through normal metabolism of drugs, environmental chemicals and other xenobiotics as well as endogenous chemicals especially stress hormones.

Antioxidant activity-
Dried powdered  of Psidium guajava was successively extracted with acetone, methanol and water respectively and subjected to antioxidant activity. Methanolic and aqueous extracts was used for the evaluation of antioxidant activity. The activity was determined at ambient temperature by means of a 2,2-diphenyl1-1-picrylhydryzyl (DPPH) spectrophotometrically with detection scheme at 520 nm. the activity was evaluated by the decrease in absorbance as the result of DPPH colour change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that methanol extract has almost same antioxidant activity as of ascorbic acid while aqueous extract showed less antioxidant activity. This study revealed that guava stem extracts comprise effective potential source of natural antioxidants which might be helpful in preventing the progress of various oxidative stresses.

The methanolic extract of Psidium guajava L. exhibited a maximum total antioxidant activity of 79.37 % at 100 μg/ml whereas for ascorbic acid (standard) was found to be 80.56 % at 100 μg/ml. the IC50 values of the methanolic extract of Psidium guajava and ascorbic acid were found to be 33.95μg/ml and 30.28μg/ml respectively. the aqueous extract of Psidium guajava exhibited a maximum total antioxidant activity of73.56 % at 100 μg/ml whereas for ascorbic acid(standard) was found to be 80.56 % at 100 μg/ml.the IC50 values of the aqueous extract of Psidium guajava and ascorbic acid were found to be40.16μg/ml and 30.28μg/ml respectively.


Psidium guajava leaves have long been recognized for their antimicrobial activity. the phytochemical analysis was observed that the Psidium guajava contains alkaloids, flavanoids, phenols andtannin which may either individual or in combination are responsible for the antibacterial activity. From the observed results, it could be concluded that Psidium guajava leaves could serve as good source of antibacterial and antifungal agents.

In vitro antimicrobial activity against Escherichia coli, Salmonella typhi, Staphylococcus aureus, Proteus mirabilis, and Shigelladysenteria .  the effectiveness of the leaf extras against Staphylococcus aureus also found. It was shown to strong antibacterial activity and in addition to Staphylococcus aureus was also useful against  Streptococcus spp.  The leaves are rich in tannin, and have antisepticproperties.

A strong antimicrobial action of guava leaves on Gram-positive and Gram-negativeorganisms has been reported and also noted action on Mycobacterium phlei. The flavones derivatives isolated were reported to inhibit the growth of Staph. aureus in a dilution of 1:10,000.The bark was also shown to exhibit antibacterial, it might be , the effectiveness of Guava as an antimicrobial was confirmed by Four antibacterial compounds were isolated from leaves of guava (P. guajava) new flavonoid glycosides, morin-3-O-α-L-lyxopyranoside and morin-3-O-alpha-L are abopyranoside, and two known flavonoids, guaijavarin and quercetin.

Psidium guajava and bark tincture was subjected to invitro sensitivity test by serial dilution at concentration ranging from 5% to 15% against six test dermatophytes viz. Trichophyton tonsurans, T. rubrum, Trichosporon beigelii, Microsporum fulvum, M. gypseum and Candida albicans. Bark tincture has higher efficacy in controlling the mycelial growth of dermatophytes than the leaves tincture. The tincture showed fungicidal property in different concentrations but exhibited only fungistatic property in case of C. albicans. A leaf extract enters into a Nigerian remedy for skin infections, and examination showes positive action on gram positive microbial organism as well as on gram negative microorganism but less than action on gram positive microbes. Three antibacterial substances have been detected in the leaves which are derivatives of quercetine. As in the  polyphenols and many other substances are present.

This  antimciriobial property of psidium guajava linn. Useful for-

  • developing topical antimicrobial agent .like(soaps, antiacne cream, lotion)
  • Antiseptic.
  • Mouth ailments (dental queries,antiplaque)- mouthwashes
  • Vaginal discharge
  • In treatment  of infantile rotaviral enteritis

About 2.2 million people in developing countries are suffering from diarrhea. aqueous extract of the leaves of Psidium guajava L. were assessed for the antidiarrhoeal activity in male Sprague-Dawley rats with morphine as the standard drug (dose: 0.2 ml/kg). Quercetin and quercetin-3-arabinoside, extracted from the buds and leaves of Psidium guajava L. at concentrations of 1.6 μg/ml showed a morphine like inhibition of acetylcholine release in the coxially stimulated ileum together with an initial increase in muscular tone, followed by a gradual decrease. It is also reported that the Asiatic acid, extracted from the leaves showed dose dependent(10-500 μg/ml) spasmolytic activity in spontaneously contracting isolated rabbit jejunum.

In a study carried out with methanol extract from leaves (8 μg/ml) of Psidium guajava showed activity against simian (SA-11) rotavirus 93.8% inhibition. In addition, galactose specific lectin in guava was shown to bind to Escherichia coli (a common diarrhea causing organism), preventing its adhesion to the intestinal wall and thus preventing infection resulting diarrhea.

Researches showed that the guava has potent antidiarrhoeal  activity like that morphine ,but we well know that the side effects of morphine (which is very dangeres) in that case PSIDIUM GUAJAVA LINN. is hold greater importance because of its negligible toxicity as well as potent effect. the isolated compounds are used in pharmaceutical.

Psidium guajava
is one of the most widely used plant as herbal remedy for the treatment of Diabetes mellitus. In the present study the hydro alcoholic extracts of the fresh and dry leaves of this plant are therapeutically evaluated and compared for anti-hyperglycemic potential against Alloxan induced Diabetes in Rats. The animals were administered with doses of 500mg/kg body weight of extract orally to Alloxan induced rats continuously for 30days, caused significant reduction in the fasting serum blood glucose levels. Among the two extracts fresh leaf extract showed significant anti hyperglycemic activity than the dry leaf extract which nearly produced equal reduction in serum blood glucose levels to that of standard glibenclamide 10mg/kg.

Studies revealed that the plant contains good anti-diabetic potential, with increase in the body weights of the animals. As per the literature review the plant also contains anti-oxidant properties . So free radical scavenging property exists for the compound which may play a key role in minimising the microvascular and macrovascular complications of diabetes mellitus.



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